Anti-backlash coupler

ABSTRACT

Disclosed are devices, systems, assemblies, couplers, and other implementations, including a coupler that includes a first coupling element matingly engaged to a second coupling element, each of the first and second coupling elements including a plate defining an opening, a projection extending from a first surface of the plate, and a socket extending from a second surface of the plate and configured to receive a rotatable member. The projection of the first coupling element is received in the opening of the plate of the second coupling element, and the projection of the second coupling element is received in the opening of the plate of the first coupling element. The matingly engaged coupling elements are configured to rotate in response to rotation of a first rotatable member of a first device received in the socket of the first coupling element.

BACKGROUND

Rotary Sensors (e.g., sensors implemented using rotary variabledifferential transformers, or RVDT, potentiometer-based sensors, etc.)are generally used when accurate determination of the angular positionof a structure is required. For example, it is important to determine,and if necessary to correct, the angular position and/or orientation ofthe wheels of a landing gear of an aircraft (e.g., if, during landing,the wheels are turned at an angle relative to the longitudinal axis ofthe fuselage, the wheels may break).

To enable accurate measurement of the angular position of the structurein question, in some situations multiple rotary sensors may be employed.In such situations, it is important to ensure that connecting multiplesensors to the structure whose angular position is to be determined(e.g., by connecting sensors in, for example, a series arrangement) doesnot result in in misalignment between the sensors, or in backlash, whichcould affect the accuracy of the measurements.

SUMMARY

Disclosed are assemblies, systems, devices and methods to determineangular position of a structure (e.g., angular position of the nosewheel of an aircraft) that include, for example, a coupler including afirst coupling element matingly engaged to a second coupling element,with each of the first and second coupling elements comprising a platedefining an opening, a projection extending from a first surface of theplate, and a socket extending from a second surface of the plateconfigured to receive a rotatable member (e.g., a rotatable shaft). Theprojection of the first coupling element is received in the opening ofthe plate of the second coupling element, and the projection of thesecond coupling element is received in the opening of the plate of thefirst coupling element. The matingly engaged coupling elements areconfigured to rotate in response to rotation of rotatable member of afirst device (e.g., a rotary sensor) received in the socket of the firstcoupling element.

Implementations provided herein are configured to enable multiplechannels of tandem rotary sensors (such as potentiometers, RVDT andresolvers) to be coupled to one another. Such a coupling may beperformed blindly (i.e., it is unnecessary, when using the couplers andassemblies such as those described in this disclosures, to carefullyalign the sensors with respect to each other). The couplers describedherein may achieve, for example: 1) preventing side loading of RVDTshafts in case of a linear misalignment or an angular misalignment, 2)transferring the angular position from one sensor to another withminimum backlash. The implementations provided herein enable avoidingbacklash when transferring rotary motion from one channel to another. Insome embodiments, the implementations provided herein are configured toovercome angular and axial misalignment. The implementations providedherein also avoid angular shift (i.e., tracking between channels) due totemperature variation.

The implementations described herein include multiple rotary sensors(e.g., RVDT, Resolver, etc.) connected in a tandem arrangement (e.g., aseries connection arrangement) to enable multi load path. Thus, in theevent of failure of one sensor, other coupled sensors can take over. Thecoupler implementations described herein may be constructed from solidbar stock, and may be welded or otherwise attached to the end of theshaft of a rotary sensor to thus enable tandem attachment of multiplechannels of sensors. In some embodiments, the couplers described hereinmay be used, for example, in an aerospace environment where trackingbetween channels is important (i.e., so as to obtain multipleindependent measures to determine and/or improve the accuracy of themeasurements).

Thus, in some embodiments, a coupler is disclosed. The coupler includesa first coupling element matingly engaged to a second coupling element,each of the first and second coupling elements including a platedefining an opening, a projection extending from a first surface of theplate, and a socket extending from a second surface of the plate andconfigured to receive a rotatable member. The projection of the firstcoupling element is received in the opening of the plate of the secondcoupling element, and the projection of the second coupling element isreceived in the opening of the plate of the first coupling element. Thematingly engaged coupling elements are configured to rotate in responseto rotation of a first rotatable member of a first device received inthe socket of the first coupling element.

Embodiments of the coupler may include at least some of the featuresdescribed in the present disclosure, including one or more of thefollowing features.

The plate of each of the first coupling element and the second couplingelement may include a disc section, and a leaf spring extending from thedisc section such that the leaf spring and the disc section define theopening.

The leaf spring may integrally extend from the disc section.

The leaf spring of the first coupling element may extend in a firstdirection substantially opposite a second direction at which the leafspring of the second coupling element extends.

The projection extending from the plate of each of the first couplingelement and the second coupling element may include a pin.

The socket of each of the first coupling element and the second couplingelement may include a hollow tube with an open end, the hollow tubeextending from the second surface of the plate may be configured toreceive the rotatable member through the open end of the hollow tube.

The first rotatable member of the first device may be a shaft of arotatory sensor. The rotary sensor may include one of, for example, arotary variable differential transformer (RVDT) sensor, a resolversensor, and/or a potentiometer-based sensor.

The coupler may be configured to enable serial connection of multiplerotary sensors without causing backlash from the serial connection ofthe multiple sensors.

In some embodiments, an assembly is disclosed. The assembly includes acoupler comprising a first coupling element matingly engaged to a secondcoupling element, each of the first and second coupling elementsincluding a plate defining an opening, a projection extending from afirst surface of the plate, and a socket extending from a second surfaceof the plate and configured to receive a rotatable member. The assemblyfurther includes a first device comprising a first rotatable shaftreceived in the socket of the first coupling element, and a seconddevice comprising a second rotatable shaft received in the socket of thesecond coupling element. Rotation of the first shaft of the first devicewill cause rotation of the coupler and of the second shaft of the seconddevice received in the socket of the second coupling element of thecouplers.

Embodiments of the assembly may include at least some of featuresdescribed in the present disclosure, including at least some of thefeatures described above in relation to the coupler, as well as one ormore of the following features.

The first shaft of the first device may be a shaft of a first rotarysensor, and the second shaft of the second device may be a shaft of asecond rotary sensor.

One or more of the first rotary sensor and the second rotary sensor mayinclude one or more of, for example, a rotary variable differentialtransformer (RVDT) sensor, a resolver sensor, and/or apotentiometer-based sensor.

In some embodiments, an assembly is disclosed. The assembly includes twoor more couplers each comprising a first coupling element matinglyengaged to a second coupling element, each of the first and secondcoupling elements including a plate defining an opening, a projectionextending from a first surface of the plate, and a socket extending froma second surface of the plate and configured to receive a rotatablemember. The assembly also includes a first device comprising a firstrotatable shaft received in the socket of the first coupling element ofone of the two or more couplers, a second device comprising a secondrotatable shaft, the second rotatable shaft including a first endreceived in the socket of the second coupling element of the one of thetwo or more couplers and a second end received in the socket of thefirst coupling element of another of the two or more couplers. Theassembly further includes an additional device including an additionalrotatable shaft received in the socket of the second coupling element ofthe other of the two or more couplers. Rotation of the first shaft ofthe first device will cause rotation of the two or more couplers, thesecond shaft of the second device, and the additional shaft of theadditional device.

Embodiments of the assembly may include at least some of featuresdescribed in the present disclosure, including at least some of thefeatures described above in relation to the coupler and the firstassembly, as well as one or more of the following features.

The first shaft of the first device may be a shaft of a first rotarysensor, the second shaft of the second device may be a shaft of a secondrotary sensor, and the additional shaft of the additional device may bea shaft of a third rotary sensor.

One or more of the first rotary sensor, the second rotary sensor, andthe third rotary sensor may include one or more of, for example, arotary variable differential transformer (RVDT) sensor, a resolversensor, and/or a potentiometer-based sensor.

As used herein, the term “about” refers to a +/−10% variation from thenominal value. It is to be understood that such a variation is alwaysincluded in a given value provided herein, whether or not it isspecifically referred to.

As used herein, including in the claims, “and” or “or” as used in a listof items prefaced by “at least one of or “one or more of indicates thatany combination of the listed items may be used. For example, a list of“at least one of A, B, and C” includes any of the combinations A or B orC or AB or AC or BC and/or ABC (i.e., A and B and C). Furthermore, tothe extent more than one occurrence or use of the items A, B, or C ispossible, multiple uses of A, B, and/or C may form part of thecontemplated combinations. For example, a list of “at least one of A, B,and C” may also include AA, AAB, AAA, BB, etc.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs.

Details of one or more implementations are set forth in the accompanyingdrawings and in the description below. Further features, aspects, andadvantages will become apparent from the description, the drawings, andthe claims.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A-B are perspective diagrams of an example embodiment of acoupler in a disengaged (FIG. 1A) and engaged (FIG. 1B) states.

FIG. 1C is a perspective diagram of one coupling element of the couplerof FIGS. 1A and 1B.

FIG. 2A is a perspective diagram of an assembly which includes a couplercoupled to two rotatable member of two devices.

FIG. 2B is a perspective diagram of a disengaged coupler with twocoupling elements that are each coupled to a rotatable member.

FIGS. 3A-B are perspective diagrams of an example RVDT sensor assemblythat includes multiple rotary sensors that may be coupled to each otherusing the couplers and assemblies of FIGS. 1A-C and 2A-B.

FIGS. 4A and 4B are diagrams of an example embodiment of an assemblyincluding two couplers and at least three rotary sensors.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Disclosed herein are assemblies, systems, devices and methods, includinga coupler that includes a first coupling element matingly engaged to asecond coupling element, each of the first and second coupling elementscomprising a plate defining an opening, a projection extending from afirst surface of the plate, and a socket extending from a second surfaceof the plate and configured to receive a rotatable member. Theprojection of the first coupling element is received in the opening ofthe plate of the second coupling element, and the projection of thesecond coupling element is received in the opening of the plate of thefirst coupling element. The matingly engaged coupling elements areconfigured to rotate in response to rotation of a first rotatable membershaft of a first device received in the socket of the first couplingelement.

FIGS. 1A-B are perspective diagrams of an example embodiment of acoupler 100 in a disengaged (FIG. 1A) and engaged (FIG. 1B) states. FIG.1C is a diagram of one coupling element 110 of the coupler 100 shown inFIGS. 1A and 1B. The coupler 100 is configured to couple at least tworotatable members (e.g., shafts) of separate and independent rotarysensors (e.g., a rotary variable differential transformer) such thatrotational actuation by an external rotatable structure will cause thesame angular rotation by the at least two rotary sensors, and thusenables independent angular measurements of the extent of rotationundergone by the external rotatable structure. In some embodiments, thecoupler 100 may also be used to couple other types of rotatable devices.The coupler 100 includes a first coupling element 110 configured to bematingly engaged to a second coupling element 120. In some embodiment,the second coupling element 120 may be similar in its configuration tothe first coupling element 110, except that the coupling element 120 maybe aligned as a mirror opposite of the coupling element 110 and rotatedat approximately 180° relative to the coupling element 110. In someembodiments, the coupling elements 110 and 120 need not be mirroropposites of each other, and may have different configurationsstructured so as to enable the separate coupling elements to matinglyengage each other such that the separate coupling elements undergo thesame rotation in response to rotation of a rotatable structure that isphysically coupled to one of the engaged coupling elements.

As further shown in FIG. 1A and 1C, in some embodiments, the couplingelement 110 includes a plate 112 defining an opening 114, a projection116 extending from a first surface 113 of the plate 112, and a socket118 extending from a second surface of the plate (the second surface ishidden from view in the perspective diagrams of FIGS. 1A and 1C) andconfigured to receive a rotatable member of one of the rotary sensorsthat is to be coupled by the coupler 100. Likewise, the second couplingelement (shown in FIGS. 1A-B) may include a plate 122 defining anopening 124, a projection 126 extending from a first surface of theplate 122 of the second coupling element (the first surface of the plateof the second coupling element is hidden from view in the perspectivediagrams of FIGS. 1A and 1B), and a socket 128 extending from a secondsurface 125 of the plate 122 of the second coupling element 120.

When the two coupling elements constituting the coupler 100 are matinglyengaged, the projection 116 of the first coupling element 110 isreceived in the opening 124 of the plate 122 of the second couplingelement 120, and the projection 126 of the second coupling element 120is received in the opening 114 of the plate 112 of the first couplingelement 110. The matingly engaged coupling elements are configured torotate in response to rotation of a rotatable member (such as arotatable shaft) of a rotatable device, such as a rotary sensor, whenthe rotatable member is received in the socket of the first couplingelement. The assembled coupler 100 (i.e., when its two coupling elementsare matingly engaged, as more particularly shown in FIG. 1B) isgenerally held (or suspended/supported) by the rotatable membersreceived in the coupler's sockets, and generally does not otherwise needto be supported by some supporting structure. Thus, rotation of therotatable member received in the socket of the first coupling element(e.g., the socket 118) will cause rotation of the first coupling elementthrough the same angular displacement as that undergone by the rotatablemember. Because the second coupling element is matingly engaged to thefirst coupling element, the second coupling element will also be rotatedthrough the same angular displacement as that of the first couplingelement and as that of the rotatable member, thus causing a secondrotatable member received in the socket of the second coupling element(e.g., the socket 128) to also rotate through the same angulardisplacement. Accordingly, because the two rotatable members (e.g., oftwo rotary sensors) coupled to the coupler 100 undergo the samerotational angular displacement, the rotary sensors whose rotatablemembers are coupled to the coupler 100 will be able to measuresubstantially the same angular displacement and provide separate andindependent angular displacements/position measurements.

With continued reference to FIGS. 1A-C, in some implementations, each ofthe plates 112 and 122 of the first coupling element 110 and the secondcoupling element 120 may include a disc section (e.g., a structureresembling a round disc broken around its middle) and a leaf spring 119and 129 extending from the respective disc sections such that the leafsprings 119 and 129 and the respective disc sections define the openings114 and 124. The disc sections and respective leaf springs may beintegrally connected to each other. For example, the plates 112 and 122may each be machine carved from a single piece of material such as, forexample, a bar stock 17-7PH or 15-5PH material. Each leaf spring may bestructured to be resiliently biased inwardly such that when a projectionof one coupling element (such as the projection 126) with a diameterlarger than that of an opening defined by the leaf spring and discsection of its counterpart coupling element through which the projectionis to be received, the leaf spring can be pushed outwardly to enablepassage of the projection being received. Once received, the resilientlystructured leaf spring that was pushed outwardly will apply an inwardforce to keep the received projection from the second coupling elementin place. In some embodiments, the leaf spring 119 of the first couplingelement 110 extends in a first direction substantially opposite a seconddirection at which the leaf spring 129 of the second coupling element120 extends.

In some variations, each of the projections 116 and 126 extending fromthe plates 112 and 122 of the first coupling element 110 and the secondcoupling element 120 may include a pin. As shown in FIG. 1C, the pincorresponding to the projection 116 may include a cone section 140, amiddle section 142, and a base 144. In some implementations, the pin isconstructed separately from the plate, and is secured to the plate byfitting its base 144 into a bore (or hole) 146 defined in the plate. Thediameter of the bore 146 may be slightly smaller than the diameter ofthe base 144 of the pin so that the base 144 is press fitted into thebore 146. For example, in some embodiments, the diameter of the base 144of the pin may be larger than the diameter of the bore 146 by about0.005″ to 0.010″, depending on the configuration and size of the disc.Press fitting the base of the pin into the bore may achieve a zerobacklash performance. In some implementations, the base of the pin maybe welded, glued, threaded, or otherwise fastened to the plate, and maybe so fastened instead of or in addition to fitting the base of the pininto the bore 146. In some implementations, the pin corresponding to theprojection 116 may be an integral part of the plate, e.g., where asingle solid piece is cut (for example, machine mill cut, EDM cut, waterjet cut, etc.), or where the coupling structure is manufactured using amould, to form an integral one-piece pin-disc-socket structure.

Similarly, and as shown in FIGS. 1A and 1B, the counterpart plate 120that is to be matingly engaged to the first plate 110 may also have apin of similar construction and configuration as the pin to be securedto the plate 110. The cone section 140 of the pin of the first plate 110is configured to be received through the opening 124 defined in thesecond, opposite, plate 120 with which the first plate 110 is to bematingly engaged, with the cone section 140 passing through the opening124 up to the point where the tapered walls of the cone section 140contact the inner walls of the opening 124 and cannot be furtheradvanced through the opening.

As noted, each of the coupling elements 110 and 120 also includes asocket (e.g., the socket 118 of the coupling element 110, and the socket128 of the coupling element 120), which, in some implementations, may bea hollow tube or cylinder with an open end. In such implementations, thehollow tube of each of the coupling elements may extend from the secondsurface of the plates (e.g., the surface 125 of the plate 122 of thesecond coupling element 120), and may be configured to receive arotatable member of a rotary sensor through the open end of the hollowtube. The rotatable member (e.g., a rotatable shaft) to be received byeach of the hollow tubes may be secured to the hollow tube throughtension forces of the inner walls of the hollow tubes acting on theouter surface of the portion the rotatable members received in thehollow tubes (i.e., press fitting the rotatable member into the socket),and/or by using some other fastening mechanism (e.g., threading therotatable members into the hollow tubes, using latches, or other lockingmechanisms, that lock into slots within the inner walls of the hollowtubes, etc.) to secure the rotatable members received in the hollowtubes. In some embodiments, a shaft of each sensor coupled through thecoupler may also be secured to the coupler by welding or gluing theshaft into the coupler's sockets. The coupler may also be implemented sothat it includes a solid shaft, instead of a tube, extending from thecoupler, with such a solid shaft being received by an appropriatereceiving mechanism (e.g., a socket) included with the rotatablemember(s) the coupler is coupled to. In some embodiments, the sockets(e.g., hollow tubes) are integrally connected to the plates so that theplates and sockets constitute a single piece structure machined from,for example, bar stock such as 17-7PH or 15-5PH materials. In someembodiments, the leaf spring, disc section and socket form an integralone-piece disc-tube assembly that can be fashioned from a material(e.g., a solid-disc-shaped material) by performing a machine mill cut, awater jet cut, an Electrical Discharge Machining (EDM), etc. In someembodiments, the sockets may be separately constructed and subsequentlysecured to the plates of the coupling elements.

It should be noted that the couplers described herein are configured forredundancy, so that if, for example, the leaf spring of one coupler forany reason becomes loose or damaged, the second leaf spring will stillenable secure engagement of the coupling elements of the coupler.Likewise, a coupler's pins also enable structural redundancy of thecoupler.

In operation, the two coupling elements 110 and 120 are matingly engagedby fitting the projection 116 in the opening 124, and the projection 126in the opening 114. A rotatable member of a first rotary sensor (or someother device with a rotatable member) is received in the socket (e.g., ahollow tube) 118 of the first coupling element 110, and a rotatablemember of a second rotary sensor (or some other device with a rotatablemember) is received in the socket 128 of the second coupling element120.

More particularly, and with reference to FIG. 2A, a perspective diagramof an assembly 200, which includes a coupler 202 coupled to tworotatable members 240 and 250, is shown. FIG. 2B is another perspectivediagram of another example embodiment of an assembly 280 in which adisengaged coupler 282 (i.e., its two coupling elements are not coupledto each other) is shown. The coupler 202 of FIG. 2A and the coupler 282of FIG. 2B may be similar to the coupler 100 shown in FIGS. 1A-C. Thecoupler 202 of FIG. 2A may thus include a first and second couplingelements 210 and 220. The first coupling element 210 may include a plate212 defining an opening 214, and a projection 216 (e.g., a pin securedto the plate 212 via, for example, a bore defined in the plate 212)extending from a first surface of the plate. The plate may include adisc section and a leaf spring extending from it, and may be similar tothe disc sections and leaf springs depicted and described in relation toFIGS. 1A-C. The second coupling element likewise includes a plate 222defining an opening 224, and a projection 226. To matingly engage thecoupling elements to implement the coupler 202, the projection 216 ofthe first coupling element 210 is received in the opening 224 of thesecond coupling element 220, and the projection 226 of the couplingelement 220 is received in the opening 214 of the first coupling element210.

The rotatable member 240, which in the example embodiment of FIG. 2A isa rotatable shaft, may be used in an implementation of a first rotarysensor (not shown), whereas the rotatable member 250 (also a shaft inthe embodiment of FIG. 2A) may be used in an implementation of a secondrotary sensor (also not shown). In some embodiments, the rotary sensorsused may be rotary variable differential transformer (RVDT) sensors suchas the sensors of the sensor assembly depicted in FIGS. 3A and B.Particularly, in the perspective diagram of FIGS. 3A and 3B, an exampleRVDT-based assembly 300 includes a first RVDT sensor 310 with arotatable member, such as a rotatable shaft 312, and a second sensor 320with a rotatable member, such as a rotatable shaft 322. Theimplementations depicted by FIG. 3A also include a third RVDT sensor350, which is more particularly shown in FIG. 3B. The third RVDT sensor350 includes a rotatable shaft 352 which is coupleable to an externalrotatable member (i.e., external to the RVDT assembly 300) whose angularposition is to be determined by the RVDT sensors of the assembly 300.

As shown in FIG. 3A, the two RVDT sensors 310 and 320 are coupled via ananti-backlash coupler 330 by fitting the end 314 of the rotatable shaft312 into a first socket 332 of the coupler 330, and fitting an end 324of the second RVDT sensor 320 into a second socket 334 of the coupler330. The coupler 330 may have a structure/configuration similar to thecoupler 100 shown in FIGS. 1A-C and/or the coupler 202 shown in FIGS.2A-B. The RVDT sensor 350 may be coupled to the RVDT sensor 310 via ananti-backlash coupler 360, e.g., fitting an end of the rotatable shaft352 into one socket on a plate of a first coupling element 362 of thecoupler 360, and fitting another end of the shaft 312 into anothersocket on a plate of a second coupling element 364 of the coupler 360.The coupler 360 may also have a structure/configuration similar to thecoupler 100 shown in FIGS. 1A-C and/or the coupler 202 shown in FIGS.2A-B.

As further shown in FIG. 3A, the RVDT sensors 310 and 320 each includesa primary winding set (326, and 328) positioned proximate (e.g.,surrounding) the respective rotatable shafts 312 and 322. Each of theRVDT sensors 310 and 320 further includes a secondary windings (alsoreferred to as output windings) 318 and 328, respectively, positionedproximate the respective rotatable shafts 312 and 322 of the sensors.Disposed on the outer surface of each of the rotatable shafts 312 and322 is at least one armature (not shown in FIGS. 3A or 3B) that rotateswith rotation of the rotatable shafts 312 and 322. The armature disposedon each of the rotatable members may be constructed from a solidmagnetic material and may be welded or bonded to the rotatable members,or may be secured to the respective members in some other suitable way.When voltage (e.g., AC voltage) is applied to the primary winding sets316 and 326, resultant voltages will be induced/produced at therespective secondary winding sets 318 and 328 set. Because the armaturessecured to the rotatable members change the inductance of the windingsas the armatures rotate, the voltage levels at the secondary windingswill vary and be based, at least in part, on the positions of thearmatures. Based on the resultant voltages at the secondary windings,the angular positions of the armatures disposed on the rotatable shaftsof the RVDT sensors, and therefore the angular position of a rotatableexternal structure causing rotation of the rotatable shafts (e.g., viaan interfacing device and/or via a rotatable shaft of another RVDTsensor in the assembly, such as the shaft 352 coupled to the RVDT sensor350) can be determined. Determination (computation) of the angularposition of an external rotatable structure based on measured resultantvoltages of the secondary windings may be facilitated by aprocessor-based computing system that receives the resultant voltages(measured, for example, by voltage sensors or meters) and outputs avalue indicative of a determined/computed angular position of theexternal rotatable structure.

In some implementations, RVDT sensors such as those described, forexample, in International Patent Application No. PCT/US2012/22986,entitled “ROTARY VARIABLE DIFFERENTIAL TRANSFORMER (RVDT) SENSORASSEMBLY WITH AUXILIARY OUTPUT SIGNAL,” the content of which is herebyincorporated by reference in its entirety, may be used in conjunctionwith the sensor assembly 300. In some implementations, other types ofrotary sensors, including, for example, potentiometers, resolvers, etc.,may be used in addition to, or instead of, RVDT-based sensors

Turning back to FIG. 2A, the rotatable member of 240 of a first rotarysensor is received in a socket 218, such as a hollow tube or cylinderthat is opened in at least one of its ends, and the rotatable member 250of a second rotary sensor is received in a socket 228. The sockets 218and 228 may be similar to the sockets 118 and 128 shown in FIG. 1A-C.Thus, the coupler 202 is supported (e.g., held) by the rotatable members240 and 250 received into the coupler's sockets 218 and 228,respectively. Accordingly, rotation of a first rotatable member, such asthe rotatable member 240, e.g., in response to rotation of an externalrotatable structure, will cause the coupler to rotate to the same extent(i.e., by the same angular displacement) as that of the first rotatablemember. The second rotatable member, for example, the member 250, whichis coupled to the coupler 202 via the socket 228, will also rotatethrough the same angular displacement of the coupler, and, thus of thefirst rotatable member. Therefore, the rotary sensors corresponding tothe rotatable members 240 and 250 will measure substantially the sameangular displacement or position.

Because the two rotatable members 240 and 250 depicted in FIG. 2A arenot directly connected to each other, the two sensors, therefore, do notneed to be properly aligned with each other. Put another way, the use ofa coupler similar to that shown and described in relation to FIGS. 1A-Cand 2A-B effectively compensates for any misalignment between thesensors used. The couplers described herein thus implement blindassemblies in that it is not necessary to carefully align the sensorswith respect to each other. Furthermore, because the two sensors are notdirectly mechanically connected to each other, backlash problems thatgenerally result from mechanically connecting moving devices areavoided. Thus, such couplers operate as anti-backlash couplers.Additionally, the use of couplers such as those depicted in theimplementations of FIG. 2A avoids having to directly couple two or moresensors, e.g., by directly coupling the sensors' shafts, thus avoidinghaving to make a long-lasting attachments (which may be permanent orsemi-permanent) of the two or more sensors. Because the two or moresensors do not have to be directly attached to each other, the two ormore sensors can therefore also be disengaged from each other withoutcausing any permanent damage to any of the sensor's bearings.

In some implementations (and as was also depicted in FIGS. 3A-B),multiple couplers, each of which may be similar to the couplers 100and/or 202 described herein, may be used to couple a plurality of rotarysensors (e.g., in a series arrangement) to enable, for example, three ormore independent measures of the angular position of a structure. Thus,with reference to FIGS. 4A and 4B, diagrams of an example embodiment ofan assembly 400, which includes two couplers 402 and 404 and at leastthree rotary sensors, are shown. The couplers 402 and 404 and the rotarysensors coupled to them are housed within a hollow tube-shaped housing410. The coupler 402 is connected, through the socket of its firstcoupling element, to the rotatable member 420 of a first rotary sensor,and is connected, through a socket of its second coupling element to arotatable member 430 of a second rotary sensor. Another end of therotatable member of the second rotary sensor is received in the socketof a first coupling element of the second coupler 404. The secondcoupling element of the second coupler 404 receives a rotatable member440 of a third rotary sensor. Additional rotary sensors may be added toan assembly such as that depicted in FIGS. 4A and 4B, if required, usingadditional couplers, such as the couplers depicted and described inFIGS. 1A-C and 2A-B. As further shown in FIGS. 4A and B, in someimplementations, the assembly 400 also includes a flange 412, coupled tothe housing 410, that is configured to secure the housing 410, and thecouplers and sensors disposed therein, to, for example, an interfacingdevice that connects to the external rotatable structure whose angularposition is to be determined.

Thus, in some embodiments, an assembly is provided that includes two ormore couplers that each comprises a first coupling element matinglyengaged to a second coupling element. Each of the first and secondcoupling elements includes a plate defining an opening, a projectionextending from a first surface of the plate, and a socket extending froma second surface of the plate and configured to receive a rotatablemember. The assembly further includes a first rotatable devicecomprising a first rotatable shaft that is received in the socket of thefirst coupling element of one of the two or more couplers. Also includedis a second rotatable device comprising a second rotatable shaft with afirst end received in the socket of the second coupling element of theone of the two or more couplers and with a second end received in thesocket of the first coupling element of another of the two or morecouplers. An additional rotatable device comprising an additionalrotatable shaft is received in the socket of the second coupling elementof the other of the two or more couplers. Rotation of the first shaft ofthe first rotatable device will cause rotation of the two or morecouplers and of the second shaft of the second rotatable device and ofthe additional shaft of the additional rotatable device.

Although particular embodiments have been disclosed herein in detail,this has been done by way of example for purposes of illustration only,and is not intended to be limiting with respect to the scope of theappended claims, which follow. In particular, it is contemplated thatvarious substitutions, alterations, and modifications may be madewithout departing from the spirit and scope of the invention as definedby the claims. Other aspects, advantages, and modifications areconsidered to be within the scope of the following claims. The claimspresented are representative of the embodiments and features disclosedherein. Other unclaimed embodiments and features are also contemplated.Accordingly, other embodiments are within the scope of the followingclaims.

What is claimed is:
 1. A coupler comprising: a first coupling elementmatingly engaged to a second coupling element, each of the first andsecond coupling elements comprising: a plate defining an opening, aprojection extending from a first surface of the plate, and a socketextending from a second surface of the plate and configured to receive arotatable member; wherein the projection of the first coupling elementis received in the opening of the plate of the second coupling element,and the projection of the second coupling element is received in theopening of the plate of the first coupling element; and wherein thematingly engaged coupling elements are configured to rotate in responseto rotation of a first rotatable member of a first device received inthe socket of the first coupling element.
 2. The coupler of claim 1,wherein the plate of each of the first coupling element and the secondcoupling element comprises: a disc section; and a leaf spring extendingfrom the disc section such that the leaf spring and the disc sectiondefine the opening.
 3. The coupler of claim 2, wherein the leaf springintegrally extends from the disc section.
 4. The coupler of claim 2,wherein the leaf spring of the first coupling element extends in a firstdirection substantially opposite a second direction at which the leafspring of the second coupling element extends.
 5. The coupler of claim1, wherein the projection extending from the plate of each of the firstcoupling element and the second coupling element includes a pin.
 6. Thecoupler of claim 1, wherein the socket of each of the first couplingelement and the second coupling element comprises a hollow tube with anopen end, the hollow tube extending from the second surface of the plateis configured to receive the rotatable member through the open end ofthe hollow tube.
 7. The coupler of claim 1, wherein the first rotatablemember of the first device is a shaft of a rotatory sensor.
 8. Thecoupler of claim 7, wherein the rotary sensor includes one of: a rotaryvariable differential transformer (RVDT) sensor, a resolver sensor, anda potentiometer-based sensor.
 9. The coupler of claim 1, wherein thecoupler is configured to enable serial connection of multiple rotarysensors without causing backlash from the serial connection of themultiple sensors.
 10. An assembly comprising: a coupler comprising afirst coupling element matingly engaged to a second coupling element,each of the first and second coupling elements comprising: a platedefining an opening, a projection extending from a first surface of theplate, and a socket extending from a second surface of the plate andconfigured to receive a rotatable member; a first device comprising afirst rotatable shaft received in the socket of the first couplingelement; and a second device comprising a second rotatable shaftreceived in the socket of the second coupling element; wherein rotationof the first shaft of the first device will cause rotation of thecoupler and of the second shaft of the second device received in thesocket of the second coupling element of the coupler.
 11. The assemblyof claim 10, wherein the plate of each of the first coupling element andthe second coupling element comprises: a disc section; and a leaf springextending from the disc section such that the leaf spring and the discsection define the opening.
 12. The assembly of claim 10, wherein theprojection extending from the plate of each of the first couplingelement and the second coupling element includes a pin.
 13. The assemblyof claim 10, wherein the socket of each of the first coupling elementand the second coupling element comprises a hollow tube with an openend, the hollow tube extending from the second surface of the plate isconfigured to receive the rotatable member through the open end of thehollow tube.
 14. The assembly of claim 10, wherein the first shaft ofthe first device is a shaft of a first rotary sensor, and the secondshaft of the second device is a shaft of a second rotary sensor.
 15. Theassembly of claim 14, wherein one or more of the first rotary sensor andthe second rotary sensor include one or more of: a rotary variabledifferential transformer (RVDT) sensor, a resolver sensor, and apotentiometer-based sensor.
 16. An assembly comprising: two or morecouplers each comprising a first coupling element matingly engaged to asecond coupling element, each of the first and second coupling elementscomprising: a plate defining an opening, a projection extending from afirst surface of the plate, and a socket extending from a second surfaceof the plate and configured to receive a rotatable member; a firstdevice comprising a first rotatable shaft received in the socket of thefirst coupling element of one of the two or more couplers; a seconddevice comprising a second rotatable shaft, the second rotatable shaftincluding a first end received in the socket of the second couplingelement of the one of the two or more couplers and a second end receivedin the socket of the first coupling element of another of the two ormore couplers; and an additional device comprising an additionalrotatable shaft received in the socket of the second coupling element ofthe other of the two or more couplers; wherein rotation of the firstshaft of the first device will cause rotation of the two or morecouplers, the second shaft of the second device, and the additionalshaft of the additional device.
 17. The assembly of claim 16, whereinthe plate of each of the first coupling element and the second couplingelement comprises: a disc section; and a leaf spring extending from thedisc section such that the leaf spring and the disc section define theopening.
 18. The assembly of claim 16, wherein the projection extendingfrom the plate of each of the first coupling element and the secondcoupling element includes a pin.
 19. The assembly of claim 16, whereinthe socket of each of the first coupling element and the second couplingelement comprises a hollow tube with an open end, the hollow tubeextending from the second surface of the plate is configured to receivethe rotatable member through the open end of the hollow tube.
 20. Theassembly of claim 16, wherein the first shaft of the first device is ashaft of a first rotary sensor, the second shaft of the second device isa shaft of a second rotary sensor, and the additional shaft of theadditional device is a shaft of a third rotary sensor.
 21. The assemblyof claim 20, wherein one or more of the first rotary sensor, the secondrotary sensor, and the third rotary sensor include one or more of: arotary variable differential transformer (RVDT) sensor, a resolversensor, and a potentiometer-based sensor.